Method and apparatus for aperture controlled electrostatic image reproduction or constitution

ABSTRACT

The invention basically comprises apparatus and methods relating to the field of electrostatics, and is concerned with electrostatic reproducing or constituting. Apertured screen means carry charge distributions in accordance with a pattern such that particles directed at the screen means pass therethrough under modulation control dictated by the pattern. The invention further relates to apparatus and methods for constituting or reproducing images through the use of a multilayered screen consisting of an array of apertures. A propulsion field directs charged particles through the screen to a receiving medium preferably spaced at a distance from the screen. Charge distribution on the screen controls the flow of particles through the apertures, some of which are in effect blocked, partially blocked, unblocked, and enhanced, depending on the local charge level. Thus, it is possible to produce patterns of varying tone without contact with the printed or effected substrate.

United States Patent Pressman et al.

Thomas D. Kittredge, South San Francisco, both of Calif.

[ Nov. 20, 1973 Mayo et al 355/16 X McFarlane 355/3 Primary ExaminerRobert P. Greiner Attorney-Wilfred G. Caldwell [73] Assignee: Electroprint, Inc., Palo Alto, Calif. methods relating to the field of electrostatics, and is [22] Filed, Jul 28 1971 concerned with electrostatic reproducing or constituty ing. Apertured screen means carry charge distribu- [21] Appl. No.: 167,007 tions in accordance with a pattern such that particles Related U S Application Data directed at the screen means pass therethrough under modulation c trol d' tated b the ttern. [62] Division of Ser. No. 776,146, Nov. 15, 1968, Pat. No. on C y pa 3,647,291 The invention further relates to apparatus and methods for constituting or reproducing images 52 us. c1. 355/3, 355/16, 96/1 R, through the use of a multi-layered Screen consisting of 96/12 an array of apertures. A propulsion field directs 51 Int. Cl G03g 15/00 charged Particles through the Screen receiving [58] Field or Search 355/3, 16, 17; medium Preferably Spaced at a distance from the 96/1 R, 12 screen. Charge distribution on the screen controls the flow of particles through the apertures, some of which [56] Reierences Cited are in effect blocked, partially blocked, unblocked, UNITED STATES PATENTS and enhanced, depending on the local charge level. Thus, it is possible to produce patterns of varying tone gag 2 55;3 2: 33 without contact with the printed or effected substrate. 3:185:05! 5 1965 Goffe 355 17 x 9 Claims, 68 Drawing Figures 6 5 420 fia- L- g g TIMER K SUBSTRATE TO BE PRINTED }AREA TO BE PRINTED- |5 SINGLE SIGN I iLgC i l j REA lll ACTUAL BLOCKED AREA 1. 1 l l l W PAWS FIGJ INSULATOR 2' CONDUCTOR HOLE FIGZ Pmmnuuuvzo ms 3773.417

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1. An aperture controlled electrostatic camera comprising in combination a housing; a removable multi-layer apertured screen comprising at least a screen insulator layer overlying a screen conductive layer; optical means for introducing an image to the housing; and charging means for double charging the insulator layer with charges varying from at least one polarity to zero in accordance with the image to be reproduced; said charging means comprising a transparent conductive layer and a photoconductive layer interposed between the screen and the optical means; and terminals whereat a source of potential is adapted to be connected between the conductive layer of the screen and the transparent layer.
 2. The camera of claim 1 wherein the optical means comprises a shutter and further comprising timer means for opening the shutter while connecting the source of potential.
 3. The camera of claim 2 further comprising light means within the camera under control of the timer means and means for reversing the potential of said source under control of the timer means whereby the insulator layer may be charged from one polarity through zero to reverse polarity.
 4. An aperture controlled electrostatic camera comprising in combination housing means; a removable multi-layer apertured screen comprising at least a screen photoconductive layer overlying a screen conductive layer; optical means for introducing an image to the housing; and charging means for double charging the photoconductive layer with charges varying from at least one polarity to zero in accordance with the image to be reproduced; said charging means comprising a transparent conductive layer and a transparent insulative layer interposed between the screen and the optical means; and terminals whereat a source of potential is adapted to be connected between the transparent conductive layer and the screen conductive layer.
 5. The camera of claim 4 wherein the optical means comprises a shutter and further comprising timer means for opening the shutter while connecting the source of potential.
 6. The camera of claim 5 further comprising light means within the camera under control of the timer means and means for reversing the potential of said source under control of the timer means whereby the photoconductive layer may be charged from one polarity through zero to reverse polarity.
 7. An aperture controlled electrostatic camera comprising in combination a housing; a multi-layer apertured screen removably connected to the housing having a first electrically insulative layer and a conductive layer; optical means comprising lens and shutter means for focusing an image on the first layer of the screen; a transparent conductor and a further insulative layer adapted to be disposed between the screen and the optical means with the further layer in contact with the first layer; one of said first layer and further layer comprising a photoconductor with the other comprising a non-light sensitive insulative layer; means for opening and closing the shutter means; and means for charging the first layer at least when the shutter means is open to establish an electrostatic latent image on the fIrst layer.
 8. The camera of claim 7 wherein the means for charging the first layer comprises a source of direct potential; and connections from the transparent conductor and the conductive layer respectively to opposite poles of said source.
 9. The camera of claim 8 further comprising means for reversing said connections for charging the first layer oppositely; a source of light effective for shining light against the transparent conductor; and timer means connected to the means for opening and closing the shutter means, the source of light, and the reversing means to effect precharging of the first layer by applying the charging potential and actuating the source of light; and to effect establishing of an electrostatic latent image on said first layer by reversing said connections and opening the shutter means. 